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Title: The superconducting quantum interference device microstrip amplifier: Computer models

Abstract

Computer models are presented for a microstrip amplifier based on a dc superconducting quantum interference device (SQUID). In this device, the signal is applied between one end of the spiral input coil and the square washer on which it is deposited. The amplifier exhibits substantial power gain when the signal frequency is such that a half wavelength is approximately equal to the length of the microstrip formed by the coil and the groundplane. The resonant frequency is lowered significantly by the inductance of the square washer transformed into the input coil; this reduction is consistent with predictions of a simple model and with analog simulations. With the washer grounded, the gain of the amplifier peaks at a frequency that is lowered from the unloaded resonant frequency by the damping of the resistance associated with the source. The position and magnitude of the peak are in good agreement with both a lumped circuit model and with a model representing the microstrip as a transmission line. When the counter electrode of the SQUID is grounded and the washer floats, feedback from the output of the SQUID to the input via the capacitance of the microstrip plays a major role and is wellmore » described by simulations using the transmission line model. Measurements of the input impedance of the microstrip amplifier show that the return loss can be positive or negative, depending on the sign of the feedback and whether the frequency is above or below the resonant frequency. This behavior is in good accord with simulations.« less

Authors:
;
Publication Date:
Sponsoring Org.:
(US)
OSTI Identifier:
40204966
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 88; Journal Issue: 11; Other Information: DOI: 10.1063/1.1321026; Othernumber: JAPIAU000088000011006910000001; 065023JAP; PBD: 1 Dec 2000; Journal ID: ISSN 0021-8979
Publisher:
The American Physical Society
Country of Publication:
United States
Language:
English
Subject:
24 POWER TRANSMISSION AND DISTRIBUTION; AMPLIFIERS; CAPACITANCE; COMPUTERS; DAMPING; ELECTRODES; FEEDBACK; IMPEDANCE; INDUCTANCE; POWER TRANSMISSION LINES; SQUID DEVICES; WAVELENGTHS

Citation Formats

Mu''ck, Michael, and Clarke, John. The superconducting quantum interference device microstrip amplifier: Computer models. United States: N. p., 2000. Web. doi:10.1063/1.1321026.
Mu''ck, Michael, & Clarke, John. The superconducting quantum interference device microstrip amplifier: Computer models. United States. doi:10.1063/1.1321026.
Mu''ck, Michael, and Clarke, John. Fri . "The superconducting quantum interference device microstrip amplifier: Computer models". United States. doi:10.1063/1.1321026.
@article{osti_40204966,
title = {The superconducting quantum interference device microstrip amplifier: Computer models},
author = {Mu''ck, Michael and Clarke, John},
abstractNote = {Computer models are presented for a microstrip amplifier based on a dc superconducting quantum interference device (SQUID). In this device, the signal is applied between one end of the spiral input coil and the square washer on which it is deposited. The amplifier exhibits substantial power gain when the signal frequency is such that a half wavelength is approximately equal to the length of the microstrip formed by the coil and the groundplane. The resonant frequency is lowered significantly by the inductance of the square washer transformed into the input coil; this reduction is consistent with predictions of a simple model and with analog simulations. With the washer grounded, the gain of the amplifier peaks at a frequency that is lowered from the unloaded resonant frequency by the damping of the resistance associated with the source. The position and magnitude of the peak are in good agreement with both a lumped circuit model and with a model representing the microstrip as a transmission line. When the counter electrode of the SQUID is grounded and the washer floats, feedback from the output of the SQUID to the input via the capacitance of the microstrip plays a major role and is well described by simulations using the transmission line model. Measurements of the input impedance of the microstrip amplifier show that the return loss can be positive or negative, depending on the sign of the feedback and whether the frequency is above or below the resonant frequency. This behavior is in good accord with simulations.},
doi = {10.1063/1.1321026},
journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 11,
volume = 88,
place = {United States},
year = {2000},
month = {12}
}